org.apache.derby.impl.store.access

Class UTFQualifier

java.lang.Object

org.apache.derby.impl.store.access.UTFQualifier

All Implemented Interfaces:

Qualifier

public class UTFQualifier
extends java.lang.Object
implements Qualifier

Field Summary

Fields inherited from interface org.apache.derby.iapi.store.access.Qualifier

CONSTANT, QUERY_INVARIANT, SCAN_INVARIANT, VARIANT

Constructor Summary

Constructors

Constructor and Description
UTFQualifier(int columnId, java.lang.String value)

Method Summary

Modifier and Type	Method and Description
void	clearOrderableCache() Clear the DataValueDescriptor cache, if one exists.
int	getColumnId() Get the id of the column to be qualified.
int	getOperator() Get the operator to use in the comparison.
DataValueDescriptor	getOrderable() Get the value that the column is to be compared to.
boolean	getOrderedNulls() Get the getOrderedNulls argument to use in the comparison.
boolean	getUnknownRV() Get the getOrderedNulls argument to use in the comparison.
boolean	negateCompareResult() Determine if the result from the compare operation is to be negated.
void	reinitialize() This method reinitializes all the state of the Qualifier.

Methods inherited from class java.lang.Object

equals, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Constructor Detail

UTFQualifier

public UTFQualifier(int columnId,
                    java.lang.String value)

Method Detail

getColumnId

public int getColumnId()

Get the id of the column to be qualified.

Specified by:

getColumnId in interface Qualifier

getOrderable

public DataValueDescriptor getOrderable()

Get the value that the column is to be compared to.

Specified by:

getOrderable in interface Qualifier

getOperator

public int getOperator()

Get the operator to use in the comparison.

Specified by:

getOperator in interface Qualifier

See Also:

DataValueDescriptor.compare(org.apache.derby.iapi.types.DataValueDescriptor)

negateCompareResult

public boolean negateCompareResult()

Determine if the result from the compare operation is to be negated.

If true then only rows which fail the compare operation will qualify.

Specified by:

negateCompareResult in interface Qualifier

See Also:

DataValueDescriptor.compare(org.apache.derby.iapi.types.DataValueDescriptor)

getOrderedNulls

public boolean getOrderedNulls()

Description copied from interface: Qualifier

Get the getOrderedNulls argument to use in the comparison.

Specified by:

getOrderedNulls in interface Qualifier

See Also:

Qualifier.getOrderedNulls()

getUnknownRV

public boolean getUnknownRV()

Get the getOrderedNulls argument to use in the comparison.

Specified by:

getUnknownRV in interface Qualifier

See Also:

DataValueDescriptor.compare(org.apache.derby.iapi.types.DataValueDescriptor)

clearOrderableCache

public void clearOrderableCache()

Clear the DataValueDescriptor cache, if one exists. (The DataValueDescriptor can be 1 of 3 types: o VARIANT - cannot be cached as its value can vary within a scan o SCAN_INVARIANT - can be cached within a scan as its value will not change within a scan o QUERY_INVARIANT- can be cached across the life of the query as its value will never change o CONSTANT - can be cached across executions

Specified by:

clearOrderableCache in interface Qualifier

See Also:

Qualifier.getUnknownRV()

reinitialize

public void reinitialize()

This method reinitializes all the state of the Qualifier. It is used to distinguish between resetting something that is query invariant and something that is constant over every execution of a query. Basically, clearOrderableCache() will only clear out its cache if it is a VARIANT or SCAN_INVARIANT value. However, each time a query is executed, the QUERY_INVARIANT qualifiers need to be reset.

Specified by:

reinitialize in interface Qualifier